Asymmetrical electrodes for bipolar vessel sealing

ABSTRACT

Bipolar electrosurgical instrument having a first and a second opposing jaw member at a distal end thereof, wherein each jaw member includes an outer housing, and an inner tissue engaging surface corresponding to the inner tissue engaging surface of the opposing jaw. The instruments includes the ability to move the jaw members relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue. The jaws include asymmetrical electrodes disposed on the inner tissue engaging surfaces. A first contact region of the electrode has a greater surface area than that of the second contact region. During resection procedures wider electrodes impart improved sealing energy to the patient-side vessel while providing sufficient energy to resected tissue to effect hemostasis.

BACKGROUND

1. Technical Field

The present disclosure relates to electrosurgical instruments andmethods for performing surgical procedures and, more particularly, to abipolar electrosurgical forceps having an asymmetrical electrodeconfiguration.

2. Background of Related Art

A hemostat or forceps is a simple pliers-like tool which uses mechanicalaction between its jaws to constrict vessels and is commonly used inopen surgical procedures to grasp, dissect and/or clamp tissue.Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating the tissue and bloodvessels to coagulate, cauterize and/or seal tissue. Such electrosurgicalforceps may be used during conventional (open) surgery and duringminimally-invasive (e.g., endoscopic) surgery. During minimally-invasivesurgery, endoscopic instruments are inserted into the patient through acannula, or port, which has been made with a trocar. The benefits ofminimally-invasive surgery are well known, and include decreasedoperative times, faster recovery, and improved outcomes.

Electrosurgical forceps commonly include an electrode on each opposingjaw surface. By controlling the intensity, frequency and duration of theelectrosurgical energy applied through the jaw members, and byregulating the clamping force applied by the jaws to tissue, a surgeoncan cauterize, coagulate, desiccate and/or simply reduce or slowbleeding of vessels and tissue. In particular, accurate application ofpressure is important to oppose the walls of the vessel; to reduce thetissue impedance to a low enough value that allows enoughelectrosurgical energy through the tissue; to overcome the forces ofexpansion during tissue heating; and to contribute to the end tissuethickness which is an indication of a good seal.

Many endoscopic surgical procedures require cutting blood vessels orvascular tissue. During certain endoscopic procedures, in particular,during resection procedures, vessels connecting the portion of the organbeing resected must be cut to enable a surgeon to physically remove theorgan from the patient's body. One portion of the severed vessel remainsattached to the patient's vascular system, and the other portion of thesevered vessel is removed with the resected organ.

Conventional vessel sealing instruments are often used during thesetypes of resection procedures, and apply electrosurgical sealing energyequally to the patient side of the vessel and to the resected portion ofthe vessel. This approach may have drawbacks, because while thepatient-side vessel seal must withstand in vivo fluid pressures, theresected-vessel seal need only prevent incidental leakage from theresected organ.

SUMMARY

The present disclosure relates to a bipolar forceps which includes ashaft having a first and second opposing jaw member at a distal endthereof and a drive assembly for moving the jaw members relative to oneanother from a first position, wherein the jaw members are disposed inspaced relation relative to one another, to a second position, whereinthe jaw members cooperate to grasp tissue therebetween. The forceps areconnected to a source of electrosurgical energy such that the jawmembers are capable of conducting energy through tissue heldtherebetween to effect a tissue seal. A rotating assembly may also beincluded for rotating the jaw members about a longitudinal axis definedthrough the shaft. In embodiments, the forceps includes a selectivelyadvanceable knife assembly for cutting tissue along the tissue seal.

The forceps include opposing electrodes disposed on inner facingsurfaces of the jaw members. The first jaw member includes a firstelectrode and a second electrode. The first electrode has a surface areagreater than that of the second electrode. The first and secondelectrodes may have any suitable shape, however, in an embodiment thefirst and second electrodes have an elongate shape, wherein the firstand second electrodes have a similar length, and the first electrode hasa width greater than that of the second electrode. The second jaw memberincludes counterpart (e.g., mirror-image) first and second electrodessuch that the first, larger electrode of the first jaw membercorresponds with the first, wider electrode of the second jaw member.Similarly, the second, narrower electrode of the first jaw membercorresponds with the second, narrower electrode of the second jawmember. The first and second electrodes on each jaw may be electricallycoupled or electrically independent.

The disclosed forceps may include an indicator to enable a surgeon toreadily determine the position of the first and second electrodes. Theindicator may be disposed on an outer surface of one or both jaws, onthe shaft, and/or on the rotating assembly. The indicator may provide avisual indication (e.g., an icon, an arrow, a color, or other suitablevisually-perceivable mark), a tactile indication (e.g., a raised area, arecessed area, a textured area, one or more “Braille-like” dimples, orother suitable feature perceivable by touch.)

During use, a surgeon may position the jaw assembly such that the sideof the jaws corresponding to the wider electrode is positioned towardsthe patient-side vessel and the side of the jaws corresponding to thenarrower electrode is positioned away from the patient-side vessel. Inthis manner, the wider electrodes may impart improved sealing energy tothe patient-side vessel, and reduce the amount of wasted sealing energyto the portion of the vessel being resected.

The present disclosure describes an electrosurgical bipolar forcepshaving an electrode configuration for use in bipolar electrosurgicalsealing and division, where the electrodes on one side of the jaws arelarger than the electrodes on the opposite side of the jaws. The largerpair of electrodes are capable of effecting vessel sealing (e.g.,capable of producing Ligasure™-quality tissue welds) while the smallerelectrodes are well-adapted to effecting coagulation, e.g., to minimizeblood in the surgical field. The disclosed instrument may include beequipped with an electrode and/or a blade capable of performingelectrosurgical tissue division. The intended use of this device couldbe any surgical procedure where maintaining a quality seal is necessaryon only one side of the device. An example of this is a polypectomy orlung wedge resection, where the excised portion of tissue would haveminimal seal width and possibly reduced thermal spread for betterassessment of disease states and margins. This may also allow themaximum seal width to be formed on the patient side of a resection whilemaintaining an overall smaller device footprint, a slimmer end effectorand/or jaw assembly, and the like.

Desirably, at least one of the jaw members is made from a hard anodizedaluminum having high dielectric properties. It is envisioned that theelectrodes include a non-stick coating disposed thereon which isdesigned to reduce tissue adherence.

According to another aspect of the present disclosure, anelectrosurgical forceps is disclosed. The disclosed forceps includes ashaft having a first and a second opposing jaw member at a distal endthereof. Each jaw member includes an outer housing, and an inner tissueengaging surface. Each jaw's inner tissue engaging surface correspondsto the inner tissue engaging surface of the opposite jaw. The forcepsincludes a drive assembly for moving the jaw members relative to oneanother from a first open position to a second closed position whereinthe jaw members cooperate to grasp tissue therebetween. The jaws includean electrode disposed on the inner tissue engaging surface having afirst contact region disposed adjacent to a first edge of the innertissue engaging surface, and a second contact region disposed adjacentto a second edge of the inner tissue engaging surface. The surface areaof the first contact region is greater than the surface area of thesecond contact region.

According to another embodiment, disclosed is an electrosurgical forcepshaving a shaft and a pair of opposing jaw members at a distal endthereof. Each jaw member includes an outer housing, and an inner tissueengaging surface corresponding to the inner tissue engaging surface ofthe opposing jaw. The forceps includes a drive assembly for moving thejaw members relative to one another from a first, open position to asecond, closed position wherein the jaw members cooperate to grasptissue therebetween. Each jaw includes a first electrode disposed on aninner tissue engaging surface and disposed adjacent to a first edge ofthe inner tissue engaging surface, and a second electrode disposed on aninner tissue engaging surface and disposed adjacent to a second edge ofthe inner tissue engaging surface. The surface area of the firstelectrode is greater than the surface area of the second electrode.

Also disclosed is a method of operating an electrosurgical forceps,comprising the steps of providing an electrosurgical forceps having ashaft having a first and a second opposing jaw member at a distal endthereof. Each jaw member of the provided forceps includes an outerhousing, and an inner tissue engaging surface corresponding to the innertissue engaging surface of the opposing jaw. The provided forcepsincludes a drive assembly for moving the jaw members relative to oneanother from a first, open position to a second, closed position whereinthe jaw members cooperate to grasp tissue therebetween. A firstelectrode is operably coupled to a source of electrosurgical energy anddisposed on the inner tissue engaging surface of the first jaw. Thefirst electrode has a first contact region disposed adjacent to a firstedge of the inner tissue engaging surface of the first jaw, and a secondcontact region disposed adjacent to a second edge of the inner tissueengaging surface of the first jaw. The surface area of the first contactregion of the first electrode is greater than the surface area of thesecond contact region thereof. A second electrode is operably coupled toa source of electrosurgical energy and disposed on the inner tissueengaging surface of the second jaw. The second electrode has a firstcontact region disposed adjacent to a first edge of the inner tissueengaging surface of the second jaw, and a second contact region disposedadjacent to a second edge of the inner tissue engaging surface of thesecond jaw. The surface area of the first contact region of the secondelectrode is greater than the surface area of the second contact regionthereof. The method includes the steps of closing the jaws to grasptissue therebetween, and applying electrosurgical energy to tissue viathe first electrode and the second electrode to cause a change to thetissue.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein;

FIG. 1 is a left, perspective view of an embodiment of a bipolarelectrosurgical instrument in accordance with the present disclosureshowing a housing, a shaft and a jaw assembly having an asymmetricalelectrode;

FIG. 2 is an enlarged, left perspective view of an embodiment of a jawassembly having an asymmetrical electrode in accordance with the presentdisclosure;

FIG. 3 is an enlarged, partially-exploded view of the FIG. 2 embodimentof a jaw assembly having an asymmetrical electrode in accordance withthe present disclosure;

FIG. 4 is an enlarged, left perspective view of another embodiment of ajaw assembly having an asymmetrical electrode in accordance with thepresent disclosure;

FIG. 5 is an enlarged, partially-exploded view of the FIG. 4 embodimentof a jaw assembly having an asymmetrical electrode in accordance withthe present disclosure;

FIG. 6A is an enlarged, cross-sectional view of the distal end of a jawassembly in accordance with the present disclosure showing a knifeassembly in a proximal position prior to the actuation thereof;

FIG. 6B is an enlarged, cross-sectional view of the distal end of a jawassembly in accordance with the present disclosure showing a knifeassembly in a distal position subsequent to the actuation thereof; and

FIG. 7 is a perspective view of another embodiment of a bipolarelectrosurgical instrument in accordance with the present disclosurehaving a jaw assembly that includes an asymmetrical electrode.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings, however, it isto be understood that the disclosed embodiments are merely examples ofthe disclosure, which may be embodied in various forms. Well-knownfunctions or constructions are not described in detail to avoidobscuring the present disclosure in unnecessary detail. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a basis for the claims and asa representative basis for teaching one skilled in the art to variouslyemploy the present disclosure in virtually any appropriately detailedstructure.

In the drawings and in the descriptions that follow, the term“proximal,” as is traditional, shall refer to the end of the instrumentthat is closer to the user, while the term “distal” shall refer to theend that is farther from the user. Similar reference numbers are usedfor elements that are the same or similar to elements illustrated ordescribed herein. In addition, as used herein, terms referencingorientation, e.g., “top”, “bottom”, “up”, “down”, “left”, “right”,“clockwise”, “counterclockwise”, “upper”, “lower”, and the like, areused for illustrative purposes with reference to the figures andfeatures shown therein. It is to be understood that embodiments inaccordance with the present disclosure may be practiced in anyorientation without limitation.

Referring to FIG. 1, a bipolar surgical instrument 10 is shown generallyand includes a housing 20, a handle assembly 30, a trigger assembly 70,a rotating assembly 80, and an end effector assembly 90, such as,without limitation, a forceps or hemostat, which mutually cooperate tograsp, seal, and/or divide tubular vessels and vascular tissue. Asshown, handle assemblies 30 of instrument 10 are of the pistolgrip-type, however, any suitable type of handle is envisioned within thescope of the present disclosure. The handle assembly 30 offers a surgeona gripping position from which to grasp instrument 10 and to transmit aclamping pressure to end effector assembly 90. Instrument 10 includes ashaft 12, which has a distal end 14 configured to mechanically engageend effector assembly 90, and a proximal end 16 configured tomechanically engage housing 20.

As depicted in FIG. 1, shaft 12 of instrument 10 is relativelyelongated. The relatively elongated shaft 12 of instrument 10 enablesinstrument 10 to be used in performing endoscopic surgical procedures.Shaft 12 may alternatively have a shorter, or longer, shaft than thatshown in FIG. 1, which may be desirably utilized in various endoscopicand/or open surgical procedures. Rotating assembly 80 is attached to adistal end of housing 20 and is rotatable in either direction about alongitudinal axis of the shaft 12. In some embodiments, rotatingassembly 80 is rotatable approximately 180 degrees in either directionabout a longitudinal axis of the shaft 12. Rotation of rotating assembly80 correspondingly rotates jaw assembly 90 about the longitudinal axisof shaft 12. In some embodiments, as seen in FIGS. 2 and 3, shaft 12 isbifurcated at distal end 14 thereof to form ends 14 a and 14 b, whichare configured to receive jaw assembly 90.

Instrument 10 further may include an electrical cable 60 extending fromhousing 20 which couples instrument 10 to a source of electrosurgicalenergy, e.g., a generator (not explicitly shown). In some embodiments, asource of electrosurgical energy (not explicitly shown), and/or a powersource, such as without limitation, a rechargeable battery (not shown),may be included within instrument 10, e.g., within the housing 20thereof.

Handle assembly 30 includes a first handle 50 and a second handle 40.Second handle 40 is selectively movable about a pivot (not shown) from afirst position in spaced relation relative to first handle 50 to asecond position in closer proximity relative to first handle 50 whichimparts movement of jaw members 210 and 220 relative to one another,e.g., from an open to closed position about tissue. As shown in greaterdetail in FIG. 2, jaw assembly 90 is attached to distal end 14 of shaft12 and includes a pair of opposing jaw members 210 and 220. Forillustrative purposes, jaw member 210 may be referred to as an upper jawmember 210 and jaw member 220 may be referred to as a lower jaw member220. First and second handles 40, 50 are ultimately connected to a driverod (not explicitly shown) which, together, mechanically cooperate toimpart movement of jaw members 210, 220 from an open position whereinthe jaw members 210, 220 are disposed in spaced relation relative to oneanother, to a clamping or closed position wherein, e.g., jaw members210, 220 cooperate to grasp tissue therebetween.

Jaw members 210 and 220 are seated within a cavity 18 defined betweenbifurcated ends 14 a and 14 b of shaft 12. Jaw members 210 and 220include mutually corresponding component features which cooperate topermit rotation about a pivot pin 260 to effectively grasp, seal, and/ordivide tissue. Jaw members 210, 220 each include a jaw housing 216, 226,an insulative substrate or insulator 214, 224 and an electricallyconductive surface or electrode 212, 222. Insulators 214, 224 areconfigured to securely engage the electrodes 212, 224. This may beaccomplished by, e.g., stamping, by overmolding, by overmolding astamped electrically conductive sealing plate and/or by overmolding ametal injection molded seal plate. Such manufacturing techniques producea jaw assembly having an electrode 212, 222 which is substantiallysurrounded by an insulating substrate 214, 224. Insulating substrate214, 224, electrode 212, 222, and the outer, non-conductive jaw housings216, 226 are preferably configured to limit and/or reduce many of theknown undesirable effects related to tissue sealing, e.g., flashover,thermal spread and stray current dissipation. Alternatively, jaw members210 and 220 may be manufactured from a ceramic-like material andelectrically conductive surfaces 212, 222 coated onto the ceramic-likejaw members 210, 220.

Electrodes 212, 222 may also include an outer peripheral edge which hasa radius and insulators 214, 224 that meet electrodes 212, 222 along anadjoining edge which is generally tangential to the radius and/or meetsalong the radius. At the interface, electrodes 212, 222 are raisedrelative to insulator 214, 224.

Jaw members 210, 220 may be electrically isolated from one another suchthat electrosurgical energy can be effectively transferred through thetissue to form the seal. Electrodes 212, 222 of jaw members 210, 220,respectively, may be relatively flat to avoid current concentrations atsharp edges and to avoid arcing between high points. In addition, anddue to the reaction force of the tissue when engaged, jaw members 210,220 may be manufactured to resist bending. For example, jaw members 210,220 may be tapered along the width thereof which is advantageous for tworeasons: 1) the taper will apply constant pressure for a constant tissuethickness at parallel, and 2) the thicker proximal portion of jawmembers 210, 220 will resist bending due to the reaction of the tissue.

Jaw members 210, 220 may be curved in order to reach specific anatomicalstructures. For example, dimensioning jaws 210, 220 at an angle of about50 degrees to about 70 degrees is preferred for accessing and sealingspecific anatomical structures relevant to prostatectomies andcystectomies, e.g., the dorsal vein complex and the lateral pedicles.

As best seen in example embodiments shown in FIGS. 2 and 3, electrodes212, 222 include a first, larger contact area 212 a, 222 a and a secondsmaller contact area 212 b, 222 b. Larger contact areas 212 a, 222 a arearranged in a mutually corresponding configuration with respect to jawmembers 210, 220 such that contact area 212 a mates with contact area222 a when jaw members 210, 220 are in a closed position, e.g., whengrasping tissue therebetween. Similarly, smaller contact areas 212 b and222 b are arranged in a mutually corresponding configuration such thatcontact area 212 b mates with contact area 222 b when jaw members 210,220 are in a closed position. During use, the larger contact areas ofelectrodes 212 a, 222 a may be used to grasp the patient-side of avessel and/or the smaller contact areas of electrodes 212 b, 222 b maybe used to grasp tissue, vessels, etc. slated for resection. During avessel sealing procedure, the larger contact areas of electrodes 212 a,222 a enable the delivery of electrosurgical energy at a densitysufficient to form a burst-resistant vessel seal on the patient side ofthe jaws. Conversely, the narrower electrodes 212 b, 222 b enable thedelivery of electrosurgical energy to the resection side of the jawmembers 210, 200 to produce a smaller seal.

In one envisioned embodiment, the size ratio of the larger contact area212 a, 222 a to the second smaller contact area 212 b, 222 b is about3:1, however, the size ratio may be in a range of about 1.2:1 to about10:1 and in some embodiments may range up to 100:1 or greater. In someembodiments, the width ratio of the width of the larger contact area 212a, 222 a to the second smaller contact area 212 b, 222 b is about 3:1,however, the width ratio may be in a range of about 1.2:1 to about 10:1and in some embodiments may range up to 100:1 or greater.

A conductor 310 a electrically couples electrode 212 (which includeswide electrode 212 a and narrow electrode 212 b) to a source ofelectrosurgical energy as described hereinabove. Similarly, conductor310 b electrically couples electrode 222 (e.g., wide electrode 222 a andnarrow electrode 222 b) to a source of electrosurgical energy.

In another aspect, jaw housings 216, 226 include a visual indicator 218a and 218 b that is configured to enable a surgeon to readily ascertainjaw member orientation. In the example embodiment depicted in FIGS. 2and 3, visual indicator 218 a includes an intaglio arrowhead icon formedin an outer surface of jaw housing 216 that indicates the position ofthe wide electrode 212 a. Similarly, visual indicator 212 b includes anintaglio arrowhead icon formed in an outer surface of jaw housing 216that indicates the position of narrow electrode 212 b. As shown in thedrawings, indicators 218 a and 218 b indicate the wide and narrowelectrodes 212 a, 212 b by using corresponding wide and narrow arrows218 a, 218 b. The visual indicators 218 a, 218 b may include arrows, ormay include any other icon to represent the wide and narrow electrodes212 a, 212 b, respectively. The design of visual indicators 218 a, 218 bmay include a mnemonic element that enables “at a glance” intuitiveinterpretation by the surgeon. Other envisioned indicators include alarge circle/small circle, single bar/double bar, pictograph, differentcolors, and so forth. While not explicitly shown in the figures, visualindicators may be included in lower jaw member 226 to enable a surgeonto identify electrode orientation regardless of the rotated position ofthe jaw member 216, 226. Additionally or alternatively, visualindicators 218 a, 218 b may be formed by any suitable marking technique,e.g., in raised relief, laser etching, stamping, molding, machining,pigment, ink, dye, overmolding, and the like. Additionally oralternatively, visual indicators 218 a, 218 b may be positioned on shaft12 and/or rotating assembly 80 as long as they correspond to jaw memberorientation.

As seen in FIGS. 2 and 3, in order to achieve a desired gap range (e.g.,about 0.001 to about 0.006 inches) and apply a desired force to seal thetissue, at least one jaw member 210 and/or 220 includes one or more stopmembers 239 that limit the movement of the two opposing jaws 210, 220relative to one another. Each stop member 239 is made from an insulativematerial and is dimensioned to limit opposing movement of jaw members210, 220 to within the above gap range.

A knife channel 215 may be defined through the center of jaw member 220such that a knife 305 having a distal cutting edge 306 may cut throughthe tissue grasped between jaw members 210 and 220 when jaw members 210and 220 are in a closed position, as illustrated with reference to FIGS.6A and 611. Details relating to the knife channel 215, knife 305,trigger assembly 70, and a knife actuation assembly associated therewith(not explicitly shown) are explained in limited detail herein andexplained in more detail with respect to commonly-owned U.S. Pat. Nos.7,156,846 and 7,150,749 to Dycus et al.

Housing 20 is formed from two housing halves that engage one another viaa series of mechanical interfaces to form an internal cavity for housingthe internal working components of instrument 10. For the purposesherein, the housing halves are generally symmetrical and, unlessotherwise noted, a component described with respect to a first of thehousing halves will have a similar component which forms a part of asecond of the housing halves.

As mentioned above, first handle 50 and second handle 40 of handleassembly 30 cooperate with one another and with housing 20 to activate afirst mechanical linkage (not shown) which, in turn, actuates a driveassembly (not shown) for imparting movement of opposing jaw members 210,220 relative to one another to grasp tissue therebetween.

Handle assembly 130 further includes a trigger assembly 70 thatcooperates with a knife actuation assembly (not explicitly shown) whichenables the extension of knife 305 from a first, proximal, position asdepicted in FIG. 6A, to a second, distal position as depicted in FIG. 6Bto sever tissue grasped between jaw members 210, 220. Knife 305 travelswithin knife channel 215 formed within jaws 210, 220. In an embodiment,trigger assembly 70 may include a lockout (not explicitly shown) thatinhibits actuation of knife 305 while jaws 210, 220 are in an openposition.

As discussed above, by controlling the intensity, frequency and durationof the electrosurgical energy applied to the tissue, the surgeon cancauterize, coagulate, desiccate, seal and/or simply reduce or slowbleeding. In addition, the disclosed instrument may be operated in oneof a plurality of polarity configurations to achieve specific surgicalobjectives. For example, in a vessel sealing configuration, electrodes212 a and 212 h (associated with upper jaw member 210) have a positivepolarity (e.g., active electrodes) while electrodes 222 a and 222 b(associated with lower jaw member 220) have a negative polarity (e.g.,return electrodes.) In this generally bipolar configuration, blade 305is electrically deactivated and severs tissue by physically cuttingtissue (e.g., vessel) held between jaws 210, 220. Additionally oralternatively, electrosurgical energy is delivered to a vessel graspedbetween jaws 210, 220 to effectuate the sealing of the vessel.

In another configuration adapted for cutting, blade 305 is electricallycoupled to a source of electrosurgical energy to form an active (e.g.,positive) electrode. Electrodes 212 a, 212 b, 222 a, and 222 b areconfigured as a negative, or return, electrode, During use, blade 305effectuates cutting via cutting edge 306 and/or the electrosurgicalcutting energy delivered between blade 305, cutting edge 306, andelectrodes 212 a, 212 b, 222 a, and 222 b.

In yet another embodiment depicted in FIGS. 4 and 5, a jaw assembly 290includes an upper jaw member 310 and a lower jaw member 320. Upper jawmember includes an electrode array 312 having two independent electrodes312 a and 312 b. Electrode 312 a has a greater surface area than thenarrower electrode 312 b. Correspondingly, lower jaw member 320 includesa electrode array 322 having two independent electrodes 322 a and 322 b,wherein electrode 322 a has a greater surface area than the narrowerelectrode 322 b. As can be appreciated, electrode arrays 312 and 322 arearranged in a mutually corresponding configuration wherein electrode 312a mates with electrode 322 a, and electrode 312 b mates with electrode322 b, when the jaw members 310 and 320 are in a closed configuration.

Each of the four electrodes 312 a, 312 b, 322 a, and 322 b areindependently coupled to one or more sources of electrosurgical energy.As seen in FIG. 5, electrode 312 a is coupled to a source ofelectrosurgical energy by a conductor 410 a, and electrode 312 b iscoupled to a source of electrosurgical energy by a conductor 411 a.Electrodes 322 a and 322 b are coupled to a source of electrosurgicalenergy by conductors 410 b and 411 b, respectively. In an envisionedembodiment, electrodes 312 a, 312 b, 322 a, and 322 b and knife 405 maybe independently selectively assigned to a positive or negative polarity(e.g., designated as an active or return electrode.) In this embodimenta total of 32 electrode configurations are available to the surgeon.

For example, and without limitation, wide electrodes 312 a and 322 a maybe configured in a bipolar arrangement to facilitate vessel sealing onthe patient side. On the resection (narrow electrode) side, blade 405may be configured as an active (+) electrode while narrow electrodes 312b and 322 b are configured as a return (−) electrode.

In another embodiment, electrodes may be alternatively or sequentiallyenergized, either individually or in combination, to achieve effectivelysimultaneous cutting, coagulating, sealing, etc. In another non-limitingexample, a source of electrosurgical energy may be configured toprovide, during a first time period, vessel sealing energy to a firstpair of electrodes 312 a and 322 a; during a second time period, thesource of electrosurgical energy provides coagulation energy to a secondpair of electrodes 312 b and 322 b; and during a third time period, thesource of electrosurgical energy provides cutting energy, e.g., sendingpositive cutting energy to knife 405 and receiving negative cuttingenergy at electrodes 312 a, 322 a, 312 b, and 322 b. The time periodsmay be of any duration, however it is envisioned that a time period mayhave a duration of about 0.001 second to about 0.1 second, and continuein round robin fashion during activation (e.g., while activated by thesurgeon.) Various electrode combinations, energy profiles, and sequencesthereof may be specified, modified, and/or stored for later recall anduse by a surgeon.

FIG. 7 illustrates another embodiment of an electrosurgical instrument400 in accordance with the present disclosure. Instrument 400 has agenerally scissors-like or hemostat-like structure suitable for use inopen surgical procedures. Instrument 400 includes elongated shaftportions 440 and 450 each having a proximal end 441 and 451,respectively, and a distal end 442 and 452, respectively. The instrument400 includes an end effector assembly 490 which is operably coupled todistal ends 442 and 452 of shafts 440 and 450, respectively. The endeffector assembly 490 includes pair of opposing jaw members 410 and 420which are pivotably connected about a pivot pin 430. The two opposingjaw members 410 and 420 of the end effector assembly 490 are pivotableabout pin 430 from the open position to the closed position for graspingtissue therebetween. Jaw members 410 and 420 include asymmetricalelectrodes (not explicitly shown) arranged as described hereinabove thatmay be coupled to a source of electrosurgical energy by cable assembly460. In some embodiments, a source of electrosurgical energy and/or apower source may be included in instrument 400 for “wireless” use.Instrument 400 may include at least one handswitch 480, which may be aslide switch or a pushbutton switch, that is adapted to activate thedelivery of electrosurgical energy to tissue. Instrument 400 mayadditionally or alternatively include a knife actuator 470 that isadapted to actuate a knife (not shown) for dividing tissue graspedbetween jaws 410 and 420.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

What is claimed is:
 1. An electrosurgical instrument, comprising: afirst jaw member and a second jaw member disposed adjacent a distal endof the electrosurgical instrument, wherein each jaw member includes afirst lateral side, a second lateral side, an outer housing and an innertissue engaging surface, at least one jaw member being movable relativeto the other jaw member from a first position wherein the jaw membersare disposed in spaced relation relative to one another to a secondposition wherein the jaw members cooperate for grasping tissuetherebetween; a knife channel extending centrally along a width of theinner tissue engaging surface of the first jaw member; and an electrodedisposed on the inner tissue engaging surface of the first jaw member,the electrode including a first contact area and a second contact area,the first contact area disposed between the knife channel and the firstlateral side of the first jaw member, and the second contact areadisposed between the knife channel and the second lateral side of thefirst jaw member; wherein a width of the first contact area of theelectrode is greater than a width of the second contact area of theelectrode, the width of the first contact area and the width of thesecond contact area remaining substantially uniform along a length ofthe knife channel.
 2. The electrosurgical instrument according to claim1, wherein a ratio of the width of the first contact area of theelectrode to the width of the second contact area of the electrode isabout 3:1.
 3. The electrosurgical instrument according to claim 1,wherein a ratio of the width of the first contact area of the electrodeto the width of the second contact area of the electrode is in a rangeof about 1.2:1 to about 10:1.
 4. The electrosurgical instrumentaccording to claim 1, further comprising an elongated portion defining alongitudinal axis, and a rotating assembly for rotating the jaw membersabout the longitudinal axis.
 5. The electrosurgical instrument accordingto claim 1, wherein the electrode is configured to electrically couplewith a source of electrosurgical energy.
 6. The electrosurgicalinstrument according to claim 1, further comprising a visual indicatordisposed on the outer housing of at least one jaw member, wherein thevisual indicator indicates a position of at least one of the firstcontact area of the electrode and the second contact area of theelectrode.
 7. The electrosurgical instrument according to claim 1,further comprising: a knife having a distal cutting edge and configuredto traverse between a first position where the cutting edge ispositioned proximally of the knife channel and a second position wherethe cutting edge is positioned at least partially within the knifechannel.
 8. The electrosurgical instrument according to claim 7, whereinthe knife is configured to electrically couple with a source ofelectrosurgical energy.
 9. The electrosurgical instrument according toclaim 1, wherein the first jaw member defines a longitudinal axis, andwherein the first contact area of the electrode is axially aligned withthe second contact area of the electrode.
 10. An electrosurgicalinstrument, comprising: a first jaw member and a second jaw memberdisposed adjacent a distal end of the electrosurgical instrument,wherein each jaw member includes a first lateral side, a second lateralside, and a tissue engaging surface, at least one jaw member movablerelative to the other jaw member from a first position wherein the jawmembers are disposed in spaced relation relative to one another to asecond position wherein jaw members cooperate for grasping tissuetherebetween; a knife channel extending centrally along a width of aninner tissue engaging surface of the first jaw member; and an electrodeincluding: a first portion disposed on the tissue engaging surface ofthe first jaw member and disposed between the knife channel and thefirst lateral side of the first jaw member; and a second portiondisposed on the tissue engaging surface of the first jaw member anddisposed between the knife channel and the second lateral side of thefirst jaw member, wherein a width of the first portion of the electrodeis greater than a width of the second portion of the electrode, thewidth of the first portion of the electrode and the width of the secondportion of the electrode remaining substantially uniform along a lengthof the knife channel.
 11. The electrosurgical instrument according toclaim 10, wherein the first jaw member defines a longitudinal axis, andwherein the first portion of the electrode is axially aligned with thesecond portion of the electrode.